Angle Relationships

Parallel lines are lines in a plane that never meet. They are always the same distance apart.

A transversal line is a line that crosses at least two other lines. It creates angles with those lines.

Corresponding angles are angles that are in the same position at each intersection where a transversal crosses two lines.

Alternate interior angles are angles that are on opposite sides of the transversal and inside the two lines.

Alternate exterior angles are angles that are on opposite sides of the transversal and outside the two lines.

When two lines are parallel, corresponding angles are equal.

When two lines are parallel, alternate interior angles are equal.

When two lines are parallel, alternate exterior angles are equal.

The sum of two supplementary angles is 180 degrees.

The sum of two complementary angles is 90 degrees.